Light emitting device and method of manufacture

ABSTRACT

A method of making a light emitting device includes forming an active layer between first and semiconductor layers of different conductivity types, and forming a transparent conductive layer adjacent the second semiconductor layer. The transparent conductive layer includes a first transparent conductive region contacting a first region of the second semiconductor layer and a second transparent conductive region contacting a second region of the second semiconductor layer. An electrode is formed adjacent the first semiconductor layer in vertical alignment with the second region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 USC §119 to Korean ApplicationNo. 10-2009-0128393, filed on Dec. 21, 2009, incorporated herein byreference.

BACKGROUND

1. Field

One or more embodiments described herein relate to emission of light.

2. Background

A light emitting diode (LED) is a semiconductor device that convertscurrent into light. The wavelength of emitted light varies based on thesemiconductor material used, and more specifically based on the band-gapof the semiconductor material. LEDs are commonly used as light sourcesfor displays, vehicles, and other illumination applications. However,improvements are needed in their design, performance, and manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a light emitting device according to a firstembodiment.

FIG. 2 is a view of a light emitting device according to a secondembodiment.

FIG. 3 is a view of a light emitting device according to a thirdembodiment.

FIG. 4 is a view of a light emitting device according to a fourthembodiment.

FIG. 5 is a view of a light emitting device according to a fifthembodiment.

FIGS. 6 to 11 are views showing various stages produced by oneembodiment of a method for manufacturing a light emitting device.

FIG. 12 is a view of an embodiment of a light emitting device packagethat includes any of the embodiments of the light emitting device.

FIG. 13 is a view of an embodiment of a backlight unit that includes anyof the embodiments of the light emitting device or the light emittingdevice package.

FIG. 14 is a view of an embodiment of a lighting unit that includes anyof the embodiments of the light emitting device or the light emittingdevice package.

DETAILED DESCRIPTION

FIG. 1 shows a first embodiment of a light emitting device that includesa conductive support layer 80, a reflective layer 70 on the conductivesupport layer 80, and a transparent conducting layer 60 that includes afirst transparent conducting layer 61 and a second transparentconducting layer 62 on the reflective layer 70. The light emittingdevice also has a light emitting structure layer 50 that includes asemiconductor layer 20 of a first conductivity type, an active layer 30,and a semiconductor layer 40 of a second conductivity type on thetransparent conducting layer 60, and an electrode 90 on the lightemitting structure layer 50.

The conductive support layer 80 may be formed of at least one of Cu, Ti,Cr, Ni, Al, Pt, Au, W, or a conductive semiconductor material. Thereflective layer 70 may be formed of a metal that includes at least oneof Ag, AL, Cu, Ni or another material which has a high lightreflectivity. The reflective layer 70 may be selectively formed, and itis not necessary that the reflective layer 70 is disposed between theconductive support layer 80 and the transparent conducting layer 60.

One portion of the first transparent conducting layer 61 verticallyoverlaps and may contact the light emitting structure layer 50, and theother portion of the first transparent conducting layer 61 is disposedoutside the light emitting structure layer 50. A portion at which thefirst transparent conducting layer 61 is disposed outside the lightemitting structure layer 50 (i.e., a peripheral portion of the firsttransparent conducting layer 61) may prevent fragments from beinggenerated from reflective layer 70 or conductive support layer 80, forexample, during an isolation etching process for dividing the lightemitting structure layer 50 into unit chips.

One portion of the second transparent conducting layer 62 may bedisposed under the first transparent conducting layer 61, and anotherportion of second transparent conducting layer 62 may be disposedbetween semiconductor layer 40 and reflective layer 70. The secondtransparent conducting layer 62 may have an area greater than that ofthe first transparent conducting layer 61. Also, a portion of the secondtransparent conducting layer 62 may protrude in a direction of the lightemitting structure layer 50.

The transparent conducting layer 60 may be formed of at least one oftransparent conducting oxide (TCO), transparent conducting nitride(TCN), or transparent conducting oxide nitride (TCON). Differentmaterials may be used in other embodiments.

According to one embodiment, the transparent conducting layer 60 may beformed of a material having a light transmittance of about 50% or moreand a surface resistance of about 10 Ω/sq or less. At least one of In,Sn, Zn, Cd, Ga, Al, Mg, Ti, Mo, Ni, Cu, Ag, Au, Sb, Pt, Rh, Ir, Ru, orPd may be combined with at least one of O or N to form the transparentconducting layer 60.

For example, the TCO may be one of indium-tin oxide (ITO), ZnO, aluminumdoped zinc oxide (AZO), indium zinc oxide (IZO), antimony tin oxide(ATO), zinc indium-tin oxide (ZITO), Sn—O, In—O, or Ga—O, and the TCNmay be at least one of TiN, CrN, TaN, or In—N. The transparentconducting oxide nitride may be one of indium-tin oxide nitride (ITON),ZnON, O—In—N, or indium zinc oxide nitride (IZON).

The first transparent conducting layer 61 and second transparentconducting layer 62 may be formed of the same material, and may beformed using the same or different deposition processes. These processesmay include, for example, at least one of an evaporation process, asputtering process, a spray pyrolysis process, a CVD process, a dipcoating process, a reactive ion plating process, a wet coating process,a screen printing process, or laser techniques.

The first transparent conducting layer 61 and second transparentconducting layer 62 may have electrical properties different from eachother according to the deposition processes, even though the first andsecond transparent conducting layers are formed of the same material.Also, the first transparent conducting layer 61 and second transparentconducting layer 62 may have electrical properties different from eachother, even though the first and second transparent conducting layersare formed using the same deposition process(es) and material(s).

For example, the first transparent conducting layer 61 may be formedusing a sputtering process and the second transparent conduction layer62 may be formed of the same material as that of the first transparentconducting layer 61 using an evaporation process. In this case, thefirst transparent conducting layer 61 may be formed of a material havinga work function greater than that of the second transparent conductinglayer 62.

For example, when the first transparent conducting layer 61 is formedusing the sputtering process, a plasma power may be set to a low value.When the second transparent conducting layer 62 is formed using thesputtering process, the plasma power may be set to a high value. In thiscase, the first transparent conducting layer 61 may have a work functiongreater than that of the second transparent conducting layer 62.

In the light emitting device according to the first embodiment, thefirst transparent conducting layer 61 and second transparent conductinglayer 62 may have electrical properties different from each other withrespect to the second conductivity type semiconductor layer 40 of thelight emitting structure layer 50. For example, the second transparentconducting layer 62 may have current injection performance less thanthat of the first transparent conducting layer 61 with respect to thesecond conductivity type semiconductor layer 40. That is to say, thesecond transparent conducting layer 62 may have degraded electricalconductivity when compared to the first transparent conducting layer 61.Other differences in electrical properties may exist in differentembodiments.

The first transparent conducting layer 61 may make ohmic-contact withsemiconductor layer 40, and the second transparent conducting layer 62may make schottky-contact with semiconductor layer 40. Thus, the most ofcurrent flowing between the electrode 90 and the conductive supportlayer 80 may flow into a region in which the first transparentconducting layer 61 contacts semiconductor layer 40.

At least portion of a region in which the second transparent conductinglayer 62 contacts semiconductor layer 40 may vertically overlapelectrode 90. Thus, the current flowing between electrode 90 andconductive support layer 80 may widely or mostly flow into the lightemitting structure layer 50 through the first transparent conductinglayer 61 and the semiconductor layer 40 to increase light efficiency ofthe light emitting device.

Since, according to one embodiment, the first transparent conductinglayer 61 and the second transparent conducting layer 62 are formed ofthe same material, the first transparent conducting layer 61 may not beclearly distinguished from the second transparent conducting layer 62.However, in case where the transparent conducting layer 60 (i.e., thefirst transparent conducting layer 61 and the second transparentconducting layer 62) are formed of one or the same material, the firsttransparent conducting layer 61 and the second transparent conductinglayer 62 may have electrical conductivities different from each otheraccording to their regions. More particularly, a portion verticallyoverlapping the electrode 90 may have electrical conductivity less thanthat of a portion that does not overlap the electrode 90.

For example, a region in which the first transparent conducting layer 61contacts the second conductivity type semiconductor layer 40 may be afirst region having first electrical conductivity. Also, a region inwhich the second transparent conducting layer 62 contacts the secondconductive type semiconductor layer 40 may be a second region havingsecond electrical conductivity. Although the first transparentconducting layer 61 may not be clearly distinguished from the secondtransparent conducting layer 62, at least portion of the transparentconducting layer 60 vertically may overlap the electrode 90. Thus, thetransparent conducting layer 60 may include the second region havingrelatively low electrical conductivity and the first region havingelectrical conductivity greater that that of the second region.

One or more layers of light emitting structure layer 50 may be formedfrom a GaN-based semiconductor material such as but not limited to GaN,InGaN, AlGaN, or InAlGaN. A different semiconductor material may be usedin other embodiments.

For example, semiconductor layer 20 of the first conductivity type mayinclude an N-type semiconductor layer formed of a semiconductor materialhaving, for example, a compositional formula of In_(x)Al_(y)Ga_(1-x-y)N(0≦x≦1, 0≦y≦1, 0≦x+y≦1), e.g., InAlGaN, GaN, AlGaN, AlInN, InGaN, AlN,or InN, and doped with an N-type dopant such as Si, Ge, or Sn.

The active layer 30 is a layer in which electrons (or holes) injectedthrough the first conductivity type semiconductor layer 20 meets withelectrons (holes) injected through the second conductivity typesemiconductor layer 40 to emit light by a band gap difference of anenergy band depending on a formation material of the active layer 30.

The active layer 30 may have a single quantum well structure, a multiquantum well (MQW) structure, a quantum dot structure, or a quantum wirestructure as well as one of a variety of other structures. The activelayer 30 may be formed of a semiconductor material having acompositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1,0≦x+y≦1). When the active layer 30 has an MQW structure, a plurality ofwell layers and a plurality of barrier layers may be stacked to form theactive layer 30. For example, the active layer 30 may have a cycle ofInGaN well layer/GaN barrier layer.

A clad layer (not shown) in which an N-type or P-type dopant is dopedmay be disposed above/below the active layer 30. The clad layer (notshown) may be realized by an AlGaN layer or an InAlGaN layer.

For example, the second conductivity type semiconductor layer 40 may berealized by a P-type semiconductor layer formed of a semiconductormaterial having, for example, a compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1), e.g., InAlGaN, GaN,AlGaN, AlInN, InGaN, AlN, or InN, and doped with a P-type dopant such asMg, Zn, Ca, Sr, or Ba.

According to one embodiment, the first conductivity type semiconductorlayer 20 may include a P-type semiconductor layer and the secondconductivity type semiconductor layer 40 may include the N-typesemiconductor layer. Also, a third semiconductor layer (not shown)including an N-type or P-type semiconductor layer may be disposed on thesecond conductivity type semiconductor layer 40. Thus, the lightemitting structure layer 50 may have at least one of an np junctionstructure, a pn junction structure, an npn junction structure, or a pnpjunction structure. Also, impurities may be doped into the firstconductivity type semiconductor layer 20 and the second conductivitytype semiconductor layer 40 with uniform or non-uniform concentration.

Thus, the light emitting structure layer 50 including the firstconductivity type semiconductor layer 20, the active layer 30, and thesecond conductivity type semiconductor layer 40 may have variousstructures, and is not limited to the structure of the light emittingstructure layer 50 exemplified in the embodiment.

The electrode 90 may be disposed on the first conductivity typesemiconductor layer 20 and may include at least one metal of Au, Al, orPt to easily perform a wire bonding process.

The light emitting device according to the first embodiment may controlthe flow of the current into light emitting structure layer 50 throughthe transparent conducting layer 60. Because the transparent conductinglayer 60 has a light transmittance of about 50% or more, most of thelight generated in active layer 30 may not be absorbed into thetransparent conducting layer 60, but may be reflected by the reflectivelayer 70. Thus, because most of the light is emitted to the outside(externally), the light efficiency of the light emitting device may beimproved.

FIG. 2 shows a second embodiment of a light emitting device which mayhave the same structure as the light emitting device according to thefirst embodiment except for the structure of transparent conductinglayer 60.

More specifically, in the first embodiment, the second transparentconducting layer 62 may be disposed on substantially an entire regionbetween the first transparent conducting layer 61 and reflective layer70. However, in the second embodiment, second transparent conductinglayer 62 is partially disposed between first transparent conductinglayer 61 and reflective layer 70. Thus, a portion of the reflectivelayer 70 may directly contact the first transparent conducting layer 61.

Also, it is not necessary that the reflective layer 70 should beprovided. For example, when reflective layer 70 is not disposed, aportion of a conductive support layer 80 may directly contact the firsttransparent conducting layer 61.

FIG. 3 shows a third embodiment of a light emitting device which has asame or similar structure as the first embodiment except for thestructure of the transparent conducting layer 60. In the firstembodiment, the second transparent conducting layer 62 is disposed on anentire region between the first transparent conducting layer 61 andreflective layer 70. However, in the third embodiment, a secondtransparent conducting layer 62 is not disposed between a firsttransparent conducting layer 61 and a reflective layer 70.

Instead, the first transparent conducting layer 61 is disposed insubstantially a same layer as the second transparent conducting layer 62and the first transparent conducting layer 61 and the second transparentconducting layer 62 do not vertically overlap each other. Thus, aportion of reflective layer 70 may directly contact the firsttransparent conducting layer 61, and the remaining portion of thereflective layer 70 may not directly contact the second transparentconducting layer 62.

In the third embodiment, it is not necessary that the reflective layer70 should be provided. For example, when reflective layer 70 is notdisposed, a portion of a conductive support layer 80 may directlycontact the first transparent conducting layer 61 and the remainingportion of the conductive support layer 80 may directly contact thesecond transparent conducting layer 62.

FIG. 4 shows a fourth embodiment of a light emitting device which has asame or similar structure to the first embodiment except for a structureof a transparent conducting layer 60. In the first embodiment, thesecond transparent conducting layer 62 is disposed on an entire regionbetween the first transparent conducting layer 61 and the reflectivelayer 70.

However, in the fourth embodiment, a second transparent conducting layer62 is not disposed between a first transparent conducting layer 61 andreflective layer 70. Furthermore, the first transparent conducting layer61 is disposed between a portion of the second transparent conductinglayer 62 and reflective layer 70. Thus, a portion of reflective layer 70may directly contact the first transparent conducting layer 61, and theremaining portion of the reflective layer 70 may not directly contactthe second transparent conducting layer 62.

In this embodiment, it is not necessary that the reflective layer 70 beprovided. For example, when the reflective layer 70 is not disposed, aportion of conductive support layer 80 may directly contact the firsttransparent conducting layer 61, and the remaining portion of conductivesupport layer 80 may directly contact the second transparent conductinglayer 62.

FIG. 5 shows a fifth embodiment of a light emitting device which mayhave a same or similar structure as the first embodiment except for astructure of a transparent conducting layer 60. In the first embodiment,the second transparent conducting layer 62 is disposed on substantiallyan entire region between the first transparent conducting layer 61 andthe reflective layer 70.

However, in the fifth embodiment, a second transparent conducting layer62 is not disposed between the first transparent conducting layer 61 andthe reflective layer 70, but rather may be disposed in substantially asame plane as the first transparent conducting layer 61. Moreover, firsttransparent conducting layer 61 and second transparent conducting layer62 are spaced from each other, and portions of the reflective layer 70are disposed between the first and second transparent conducting layer61 and 62. Also, those portions of reflective layer 70 may directlycontact light emitting structure layer 50.

In this embodiment, it is not necessary that the reflective layer 70should be provided. For example, when reflective layer 70 is notdisposed, a portion of a conductive support layer 80 may directlycontact the first transparent conducting layer 61 and the secondtransparent conducing layer 62, and the remaining portion of theconductive support layer 80 may directly contact a light emittingstructure 50.

FIGS. 6 to 11 show results of steps included in one embodiment of amethod that may be used to manufacture any of the embodiments of thelight emitting device.

Referring to FIG. 6, a light emitting structure layer 50 including asemiconductor layer 20 of a first conductivity type, an active layer 30,and a semiconductor layer 40 of a second conductivity type is formed ona growth substrate 10. Also, a first transparent conducting layer 61 isformed on the light emitting structure layer 50.

Although not shown, an un-doped nitride layer (not shown) including abuffer layer (not shown) may be formed on the growth substrate 10, andthen the first conductivity type semiconductor layer 20 may be formed onthe un-doped nitride layer. The substrate 10 may be formed of one ofsapphire (Al₂O₃), Si, SiC, GaAs, ZnO, or MgO, and the un-doped nitridelayer may include a GaN-based semiconductor layer. For example, anun-doped GaN layer grown by injecting trimethylgallium (TMGa) gastogether with hydrogen gas and ammonia gas into a chamber may be used asthe un-doped nitride layer.

Silane gas (SiH₄) containing trimethylgallium (TMGa) gas and N-typeimpurities (e.g., Si) together with the nitrogen gas and the ammonia gasmay be injected into the chamber to grow the first conductivity typesemiconductor layer 20. Then, the active layer 30 and secondconductivity type semiconductor layer 40 are formed on the firstconductivity type semiconductor layer 20.

As previously indicated, the active layer 30 may have a single quantumwell structure or a multi quantum well (MQW) structure. For example, theactive layer 30 may have a stacked structure of an InGaN well layer/GaNbarrier layer.

Bis(ethylcyclopentadienyl) magnesium (EtCp₂Mg) {Mg(C₂H₅C₅H₄)₂} gascontaining the trimethylgallium (TMGa) gas and P-type impurities (e.g.,Mg) together with the nitrogen gas and the ammonia gas may be injectedinto the chamber to grow the second conductivity type semiconductorlayer 40.

The first transparent conducting layer 61 is formed except at a partialregion of the second conductivity type semiconductor layer 40. A regionin which the first transparent conducting layer 61 is not formed is aregion in which at least a portion of an electrode 90 (that will bedescribed later) may vertically overlap. The first transparentconducting layer 61 may be formed using a sputtering process, forexample.

Referring to FIG. 7, a second transparent conducting layer 62 is formedon a partial region of the second conductive type semiconductor layer 40and the first transparent conducting layer 61. The second transparentconducting layer 62 may be formed, for example, using an evaporationprocess.

The first transparent conducting layer 61 and second transparentconducting layer 62 may include at least one of a transparent conductingoxide layer, a transparent conducting nitride layer, or a transparentconducting oxide nitride layer. Also, the first transparent conductinglayer 61 and second transparent conducting layer 62 may be formed of asame material.

The first transparent conducting layer 61 may have first electricalconductivity, and the second transparent conducting layer 62 may havesecond electrical conductivity less than the first electricalconductivity.

Alternatively, the first transparent conducting layer 61 may have afirst work function and the second transparent conducting layer 62 mayhave a second work function less than the first work function.

Alternatively, the first transparent conducting layer 61 may have firstspecific contact resistivity on a surface contacting the secondconductivity type semiconductor layer 62, and the second transparentconducting layer 62 may have second specific contact resistivity greaterthan the first specific contact resistivity on the surface contactingthe second conductivity type semiconductor layer 62.

Alternatively, the first transparent conducting layer 61 may makeohmic-contact with the second conductivity type semiconductor layer 40,and the second transparent conducting layer 62 may make schottky-contactwith the second conductivity type semiconductor layer 40.

The method of forming the first transparent conducting layer 61 andsecond transparent conducting layer 62 may be changed to form theembodiments in FIGS. 1 to 5.

To form the first embodiment in FIG. 1, the first transparent conductinglayer 61 is formed to expose a central portion thereof onto the secondconductivity type semiconductor layer 40, and the second transparentconducting layer 62 is formed on a central portion of the secondconductivity type semiconductor layer 40 and an entire region of thefirst transparent conducting layer 61.

To form the second embodiment in FIG. 2, the first transparentconducting layer 61 is formed to expose a central portion thereof ontothe second conductivity type semiconductor layer 40, and the secondtransparent conducting layer 62 is formed on a central portion of thesecond conductivity type semiconductor layer 40 and a partial region ofthe first transparent conducting layer 61.

To form the third embodiment in FIG. 3, the first transparent conductinglayer 61 is formed to expose a central portion thereof onto the secondconductivity type semiconductor layer 40, and the second transparentconducting layer 62 is formed on a central portion of the secondconductivity type semiconductor layer 40.

To form the fourth embodiment in FIG. 4, the second transparentconducting layer 62 is formed on a central portion of the secondconductivity type semiconductor layer 40, and the first transparentconducting layer 61 is formed on the second conductivity typesemiconductor layer 40 and a partial region of the second transparentconducting layer 62.

To form the fifth embodiment in FIG. 5, the first transparent conductinglayer 61 is formed on a central portion of the second conductivity typesemiconductor layer 40, and the second transparent conducting layer 62is formed on the second conductivity type semiconductor layer 40 tospace the second transparent conducting layer 62 from the firsttransparent conducting layer 61.

Referring to FIGS. 8 and 9, reflective layer 70 may be formed ontransparent conducting layer 60, and conductive support layer 80 may beformed on reflective layer 70.

Referring to FIGS. 10 and 11, the growth substrate 10 is removed.Although not shown, after the growth substrate 10 is removed, anisolation etching process for dividing the light emitting device intounit chips may be performed to expose a portion of the first transparentconducting layer 61 upwardly, as shown in FIGS. 1 to 5.

An electrode 90 is formed on the first conductivity type semiconductorlayer 20. The electrode 90 may be disposed to allow at least portionthereof to vertically overlap a region in which the second transparentconducting layer 62 contacts the second conductivity type semiconductorlayer 40.

FIG. 12 shows an embodiment of a light emitting device package whichincludes a main body 200, first and second electrode layers 210 and 220disposed on the main body 200, a light emitting device 100 disposed onthe main body 200 and electrically coupled to the first and secondelectrode layers 210 and 220, and a molding member 400 surrounding thelight emitting device 100. The main body 200 may be formed of a silicon,synthetic resin, or metal material and an inclined surface may be formedaround the light emitting device 100.

The first and second electrode layers 210 and 220 are electricallyseparated from each other to supply power to the light emitting device100. Also, the first and second electrode layers 210 and 220 may reflectlight generated in the light emitting device 100 to increase lightefficiency. In addition, the first and second electrode layers 210 and220 may discharge heat generated in the light emitting device 100.

The light emitting device 100 may be applied to the light emittingdevice shown in FIGS. 1 to 5, and the light emitting device 100 may bedisposed on the main body 200 or the first or second electrode layer 210or 220. Also, the light emitting device 100 may be electrically coupledto the first electrode layer 210 and/or the second electrode layer 220through a wire 200. Since a vertical-type light emitting device 100 isdescribed in this embodiment, only one wire 200 is used. However,multiple wires may be used in other embodiments and/or for other typesof LEDs.

The molding member 400 may surround the light emitting device 100 toprotect the light emitting device 100. Also, a phosphor may be containedin the molding member 400 to change a wavelength of the light emittedfrom the light emitting device 100.

A plurality of light emitting device packages may be arrayed on thesubstrate. Optical members such as a light guide plate, a prism sheet, adiffusion sheet, and/or a fluorescence sheet may be disposed on a pathof the light emitted from the light emitting device package. The lightemitting device package, substrate, and optical members may function asa backlight unit or a light unit. More specifically, lighting systemsthat include a backlight unit, lighting unit, an indicating device, alamp, or a street lamp may be formed using the embodiments describedherein.

FIG. 13 shows one embodiment of a backlight unit 1100 having a bottomframe 1140, a light guide member 1120 disposed within the bottom frame1140, and a light emitting module 1110 disposed on at least one side oran bottom surface of the light guide member 1120. A reflective sheet1130 may be disposed below the light guide member 1120.

The bottom frame 1140 may have a box shape with an opened upper side toreceive the light guide member 1120, light emitting module 1110, andreflective sheet 1130. The bottom frame 1140 may be formed of a metal orresin material, for example.

The light emitting module 1110 may include a substrate 700 and aplurality of light emitting device packages 600 mounted on the substrate700. The plurality of light emitting device packages 600 may providelight to the light guide member 1120. In the light emitting module 1110,although the light emitting device package 600 is disposed on thesubstrate 700 as an example, another embodiment may be directlydisposed.

As shown in FIG. 13, the light emitting module 1110 may be disposed onany one of a number of inner surfaces of bottom frame 1140. Thus, thelight emitting module 1110 may provide light toward at least lateralsurface of the light guide member 1120.

Also, the light emitting module 1110 may be disposed below the bottomframe 1140 to provide light toward an under surface of the light guidemember 1120. This may be varied according to a design of the backlightunit 1100.

The light guide member 1120 may be disposed within the bottom frame 1140and may receive the light provided from the light emitting module 1110to produce planar light, and then guide the planar light to a liquidcrystal panel (not shown).

For example, the light guide member 1120 may be a light guide panel(LGP). The LGP may be formed of one of a resin-based material such aspolymethylmethacrylate (PMMA), a polyethylene terephthalate (PET) resin,a poly carbonate (PC) resin, a cyclic olefin copolymer (COC) resin, or apolyethylene naphthalate (PEN) resin.

An optical sheet 1150 may be disposed above the light guide member 1120.

For example, the optical sheet 1150 may include at least one of adiffusion sheet, a light collection sheet, a brightness enhancementsheet, or a fluorescence sheet. For example, the diffusion sheet, thelight collection sheet, the brightness enhancement sheet, and thefluorescence sheet may be stacked to form the optical sheet 1150. Inthis case, the diffusion sheet 1150 may uniformly diffuse light emittedfrom the light emitting module 1110, and the diffused light may becollected into the display panel (not shown) by the light collectionsheet.

The light emitted from the light collection sheet may be randomlypolarized light, and the bright enhancement sheet may enhance a degreeof polarization of the light emitted from the light collection sheet.The light collection sheet may be, for example, a horizontal and/orvertical prism sheet, and the bright enhancement sheet may be a dualbrightness enhancement film. The fluorescence sheet may be a lighttransmitting plate or film including a phosphor.

The reflective sheet 1130 may be disposed below the light guide member1120 and may reflect the light emitted through the under surface of thelight guide member 1120 toward a light emitting surface of the lightguide member 1120. The reflective sheet may be formed of a materialhaving superior reflectance, e.g., a PET, PC, or PVC resin.

FIG. 14 shows one embodiment of a lighting unit 1200 that includes alight emitting device or light emitting device package according to anyof the embodiments described herein. Referring to FIG. 14, the lightingunit 1200 may include a case body 1210, a light emitting module 1230disposed on the case body 1210, a connection terminal 1220 disposed onthe case body 1210 to receive a power from an external power source.

The case body 1210 may be formed of a material having good thermaldissipation properties, e.g., a metal material or a resin material.

The light emitting module 1230 may include a substrate 700 and at leastone light emitting device package 600 mounted on the substrate 700. Inthe light emitting module 1110, although the light emitting devicepackage 600 is disposed on the substrate 700 as an example, the lightemitting device 100 may be directly disposed.

A circuit pattern may be printed on a dielectric to form the substrate700. For example, the substrate 700 may include a printed circuit board(PCB), a metal core PCB, a flexible PCB, and a ceramic PCB. Also, thesubstrate 700 may be formed of an effectively reflective material orhave a color on which light is effectively reflected from a surfacethereof, e.g., a white or silver color.

At least one light emitting device package 600 may be mounted on thesubstrate 700 and may include at least one light emitting diode (LED).The LED may include colored LEDs, which respectively emit light having ared color, green color, blue color, and white color and an ultraviolet(UV) LED emitting UV rays.

The light emitting module 1230 may have various combinations of the LEDto obtain color impression and brightness. For example, white, red, andgreen LEDs may be combined to form a high-color rendering index.

Also, a fluorescence sheet may be disposed on a path of light emittedfrom the light emitting module 1230. The fluorescence sheet changes awavelength of the light emitted from the light emitting module 1230. Forexample, when light emitted from light emitting module 1230 emits lightin a blue wavelength band, the fluorescence sheet may include a yellowphosphor. Thus, light emitted from the light emitting module 1230 passesthrough the fluorescence sheet to finally emit white light.

The connection terminal 1220 may be electrically coupled to the lightemitting module 1230 to provide a power to the light emitting module1230. Referring to FIG. 14, the connected terminal 1220 may bescrew-coupled to an external power source in a socket manner, butdifferent coupling arrangements may be used in other embodiments. Forexample, the connection terminal 1220 may have a pin shape and thus maybe inserted into the external power source. Alternatively, theconnection terminal 1220 may be connected to the external power sourceby a wire.

As previously described, at least one of the light guide member,diffusion sheet, light collection sheet, brightness enhancement sheet,and fluorescence sheet may be disposed on the path of light emitted fromthe light emitting module in order to obtain a desired optical effect.

Also, as previously described, because the lighting system may include alight emitting device package having superior light efficiency due tospreading characteristics of the current, the lighting system may havesuperior light efficiency.

One or more embodiments described herein provide a light emitting devicehaving a new structure, a method of manufacturing the light emittingdevice, a package of the light emitting device package, and a lightingsystem that includes the light emitting device.

One or more embodiments described herein also provide a light emittingdevice having improved light efficiency, a method of manufacturing thelight emitting device, a package for and a lighting system that includesthe light emitting device.

In one embodiment, a light emitting device comprises: a conductivesupport layer; a transparent conducting layer comprising a first regionhaving first electrical conductivity and a second region having secondelectrical conductivity less than the first electrical conductivity onthe conductive support layer; a light emitting structure layercomprising a first conductive type semiconductor layer, a secondconductive type semiconductor layer, and an active layer between thefirst conductive type semiconductor layer and the second conductive typesemiconductor layer on the transparent conducting layer; and anelectrode in which at least portion thereof is disposed in a region ofthe light emitting structure layer vertically overlapping the secondregion.

In another embodiment, a light emitting device package comprises: a mainbody; first and second electrode layers on the main body; a lightemitting device electrically connected to the first and second electrodelayers on the main body; and a molding member surrounding the lightemitting device on the main body, wherein the light emitting devicecomprises: a conductive support layer; a transparent conducting layercomprising a first region having first electrical conductivity and asecond region having second electrical conductivity less than the firstelectrical conductivity on the conductive support layer; a lightemitting structure layer comprising a first conductive typesemiconductor layer, a second conductive type semiconductor layer, andan active layer between the first conductive type semiconductor layerand the second conductive type semiconductor layer on the transparentconducting layer; and an electrode in which at least portion thereof isdisposed in a region of the light emitting structure layer verticallyoverlapping the second region.

In another embodiment, a lighting system using a light emitting deviceas a light source comprises: a substrate; and at least one lightemitting device on the substrate, wherein the light emitting devicecomprises: a conductive support layer; a transparent conducting layercomprising a first region having first electrical conductivity and asecond region having second electrical conductivity less than the firstelectrical conductivity on the conductive support layer; a lightemitting structure layer comprising a first conductive typesemiconductor layer, a second conductive type semiconductor layer, andan active layer between the first conductive type semiconductor layerand the second conductive type semiconductor layer on the transparentconducting layer; and an electrode in which at least portion thereof isdisposed in a region of the light emitting structure layer verticallyoverlapping the second region.

In another embodiment, a method of manufacturing a lighting systemcomprises: forming a light emitting structure layer on a growthsubstrate; forming a transparent ducting layer comprising a firsttransparent conducting layer contacting a first region of the lightemitting structure layer and a second transparent conducting layercontacting a second region of the light emitting structure layer;forming a conductive support layer on the transparent conducting layer;removing the growth substrate; and forming an electrode on the lightemitting structure layer exposed by removing the growth substrate toallow at least portion of the electrode to vertically overlap the secondregion, wherein the first transparent conducting layer and thetransparent conducting layer are formed of the same material as eachother using deposition processes or deposition process conditionsdifferent from each other.

In another embodiment, a method of making a light emitting devicecomprises: forming a first semiconductor layer; forming an active layeradjacent to the first semiconductor layer; forming a secondsemiconductor layer adjacent to the active layer, which is providedbetween the first and second semiconductor layers; forming a transparentconductive layer comprising a first transparent conductive regioncontacting a first region of the second semiconductor layer and a secondtransparent conductive region contacting a second region of the secondsemiconductor layer; forming a conductive support layer on thetransparent conductive layer; and forming an electrode adjacent thefirst semiconductor layer to allow at least a portion of the electrodeto vertically align with the second region, wherein the first and secondsemiconductor layers are of different conductivity types.

The first and second transparent conductive regions may be formed fromthe same or different class of materials, or from the same or differentmaterials.

If formed from the same materials or same class or materials, the firstand second transparent conductive regions may be formed using differentdeposition processes or different conditions of a same deposition. Also,one of the first or second transparent conductive regions are formedusing a sputtering process and the other of the first or secondtransparent conductive regions are formed using an evaporation process.Also, the first and second transparent conductive regions are formed tohave different work functions.

Alternatively, the first and second transparent conductive regions areformed from different materials.

Also, the first and second transparent conductive regions have differentelectrical conductivities, and/or different work functions, and/ordifferent specific contact resistivities. One of the first or secondtransparent conductive regions make ohmic-contact with the secondsemiconductor layer wherein the other of the first or second transparentconductive regions make schottky-contact with the second semiconductorlayer.

In addition, according to one variation, current flows to the secondsemiconductor layer through the first and second transparent conductiveregions at different rates or in different amounts. An amount of currentthat flows to the second semiconductor layer through the first region isgreater than an amount of current that flows to the second semiconductorlayer through the second region.

The method may further include forming a reflective layer between thefirst and second conductive regions and the conductive support layer.

Also, in one embodiment, the first and second regions lie substantiallyin a same plane. In another embodiment, the second region is spaced fromthe first region. In another embodiment, the first region contacts thesecond region.

Also, the second region may be made from a material which extendsbetween the first region and the conductive support layer. A sum of awidth of the material which extends between the first region and theconductive support layer and a width of the second region is less than awidth of at least one of the first semiconductor layer, the activelayer, or the second semiconductor layer. Alternatively, the firstregion may be made from a material which extends between the secondregion and the conductive support layer.

It will be understood that when a layer (or film) is referred to asbeing ‘on’ another layer or substrate, it can be directly on anotherlayer or substrate, or intervening layers may also be present. Further,it will be understood that when a layer is referred to as being ‘under’another layer, it can be directly under another layer, and one or moreintervening layers may also be present. Further, the reference about‘on’ and ‘under’ each layer will be made on the basis of drawings.

In the drawings, the thickness or size of each layer is exaggerated,omitted, or schematically illustrated for convenience in description andclarity. Also, the size of each element does not entirely reflect anactual size.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments. Thefeatures of any one embodiment may be combined with one or more featuresof the remaining embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A method of making a light emitting device,comprising: forming a first semiconductor layer; forming an active layeradjacent to the first semiconductor layer; forming a secondsemiconductor layer adjacent to the active layer, wherein the activelayer is provided between the first and second semiconductor layers;forming a transparent conductive layer comprising a first transparentconductive region contacting a first region of the second semiconductorlayer and a second transparent conductive region contacting a secondregion of the second semiconductor layer; forming a conductive supportlayer on the transparent conductive layer, wherein the second region ismade from a material which extends between the first region and theconductive support layer; and forming an electrode adjacent the firstsemiconductor layer to allow at least a portion of the electrode tovertically align with the second region, wherein the first and secondsemiconductor layers are of different conductivity types, wherein one ofthe first or second transparent conductive regions makes ohmic-contactwith the second semiconductor layer and the other of the first or secondtransparent conductive regions make schottky-contact with the secondsemiconductor layer, and wherein an upper surface of the firsttransparent conductive region is partially overlapped with and coupledto a bottom surface of the second transparent conductive region.
 2. Themethod of claim 1, wherein the first and second transparent conductiveregions are formed from a same class of materials.
 3. The method ofclaim 2, wherein the first and second transparent conductive regions areformed using different deposition processes or different conditions of asame deposition.
 4. The method of claim 3, wherein one of the first orsecond transparent conductive regions are formed using a sputteringprocess and the other of the first or second transparent conductiveregions are formed using an evaporation process.
 5. The method of claim4, wherein the first and second transparent conductive regions areformed from a same material.
 6. The method of claim 5, wherein the firstand second transparent conductive regions are formed to have differentwork functions.
 7. The method of claim 1, wherein the first and secondtransparent conductive regions are formed from different materials. 8.The method of claim 1, wherein the first and second transparentconductive regions have different electrical conductivities.
 9. Themethod of claim 1, wherein the first and second transparent conductiveregions have different work functions.
 10. The method of claim 1,wherein the first and second transparent conductive regions havedifferent specific contact resistivities.
 11. The method of claim 1,wherein current flows to the second semiconductor layer through thefirst and second transparent conductive regions at different rates or indifferent amounts.
 12. The method of claim 11, wherein an amount ofcurrent that flows to the second semiconductor layer through the firstregion is greater than an amount of current that flows to the secondsemiconductor layer through the second region.
 13. The method of claim1, further comprising: forming a reflective layer between the first andsecond conductive regions and the conductive support layer.
 14. Themethod of claim 1, wherein the first and second regions liesubstantially in a same plane.
 15. The method of claim 1, wherein thesecond region is spaced from the first region.
 16. The method of claim1, wherein the first region contacts the second region.
 17. A method ofmanufacturing a lighting system, comprising: forming a light emittingstructure layer on a substrate; forming a transparent conducting layercomprising a first transparent conducting layer contacting a firstregion of the light emitting structure layer and a second transparentconducting layer contacting a second region of the light emittingstructure layer; forming a conductive support layer on the transparentconducting layer; removing the substrate; and forming an electrode onthe light emitting structure layer by removing the substrate to allow atleast portion of the electrode to vertically overlap the second region,wherein the first transparent conducting layer has first electricalconductivity and the second transparent conducting layer has secondelectrical conductivity less than the first electrical conductivity,wherein one of the first or second transparent conducting layers makesohmic-contact with the light emitting structure layer and the other ofthe first or second transparent conducting layers makes schottky-contactwith the light emitting structure layer, and wherein an upper surface ofthe first transparent conducting layer is partially overlapped with andcoupled to a bottom surface of the second transparent conducting layer.18. A method of making a light emitting device, comprising: forming afirst semiconductor layer; forming an active layer adjacent to the firstsemiconductor layer; forming a second semiconductor layer adjacent tothe active layer, wherein the active layer is provided between the firstand second semiconductor layers; forming a transparent conductive layercomprising a first transparent conductive region contacting a firstregion of the second semiconductor layer and a second transparentconductive region contacting a second region of the second semiconductorlayer, wherein the first and second transparent conductive regions areformed from different materials; forming a conductive support layer onthe transparent conductive layer; and forming an electrode adjacent thefirst semiconductor layer to allow at least a portion of the electrodeto vertically align with the second region, wherein the first and secondsemiconductor layers are of different conductivity types, and whereinone of the first or second transparent conductive regions makesohmic-contact with the second semiconductor layer and the other of thefirst or second transparent conductive regions makes schottky-contactwith the second semiconductor layer, and wherein an upper surface of thefirst transparent conductive region is partially overlapped with andcoupled to a bottom surface of the second transparent conductive region.19. A method of making a light emitting device, comprising: forming afirst semiconductor layer; forming an active layer adjacent to the firstsemiconductor layer; forming a second semiconductor layer adjacent tothe active layer, wherein the active layer is provided between the firstand second semiconductor layers; forming a transparent conductive layercomprising a first transparent conductive region contacting a firstregion of the second semiconductor layer and a second transparentconductive region contacting a second region of the second semiconductorlayer, wherein one of the first or second transparent conductive regionsmakes ohmic-contact with the second semiconductor layer, and wherein theother of the first or second transparent conductive regions makesSchottky-contact with the second semiconductor layer; forming aconductive support layer on the transparent conductive layer; andforming an electrode adjacent the first semiconductor layer to allow atleast a portion of the electrode to vertically align with the secondregion, wherein the first and second semiconductor layers are ofdifferent conductivity types and wherein an upper surface of the firsttransparent conductive region is partially overlapped with and coupledto a bottom surface of the second transparent conductive region.
 20. Themethod of claim 13, wherein the reflective layer has a bottom surfaceprotruding toward the conductive support layer at an overlapped regionof the first and second conductive regions.
 21. The method of claim 1,wherein a portion of the upper surface of the first transparentconductive region is substantially coplanar with an upper surface of thesecond transparent conductive region.